Reference Signal Generation in a Wireless Communication System

1. A method of generating a reference signal in a wireless communication system, comprising: generating a pseudo-random sequence based on a cell identity (ID) of a cell; generating a scrambling sequence based on the cell ID; generating a reference signal sequence based on the pseudo-random sequence and the scrambling sequence; generating a reference signal for the cell based on the reference signal sequence; and determining a first index and a second index based on the cell ID, wherein the generating the pseudo-random sequence includes generating the pseudo-random sequence based on the first index, and wherein the generating the scrambling sequence includes generating the scrambling sequence based on the second index.

2. The method of claim 1 , wherein the generating the pseudo-random sequence based on the first index includes generating the pseudo-random sequence as one of G possible pseudo-random sequences for G possible values of the first index, where G is an integer greater than one, and wherein the generating the scrambling sequence based on the second index includes generating the scrambling sequence as one of L possible scrambling sequences for L possible values of the second index, where L is an integer greater than one.

3. The method of claim 1 , further comprising: generating a primary synchronization code (PSC) sequence based on the second index; generating a secondary synchronization code (SSC) sequence based on the first index; generating a primary synchronization signal for the cell based on the PSC sequence; and generating a secondary synchronization signal for the cell based on the SSC sequence.

4. The method of claim 3 , wherein the PSC sequence is mapped one-to-one to the scrambling sequence based on the second index.

5. The method of claim 1 , wherein the generating the scrambling sequence includes generating the scrambling sequence based on a maximum length sequence (M-sequence) or Golay complementary sequences.

6. The method of claim 1 , wherein the scrambling sequence has same length as the pseudo-random sequence.

7. The method of claim 1 , wherein the generating the reference signal sequence includes multiplying the pseudo-random sequence symbol by symbol with the scrambling sequence to obtain the reference signal sequence.

8. The method of claim 1 , wherein the generating the reference signal includes, for each symbol period in which the reference signal is sent, mapping the reference signal sequence to a set of subcarriers used for the reference signal, and generating an orthogonal frequency division multiplexing (OFDM) symbol with the reference signal sequence mapped to the set of subcarriers, the OFDM symbol including the reference signal.

9. The method of claim 1 , further comprising: sending the reference signal periodically for use by user equipments (UEs) for channel estimation, signal strength measurement, signal quality measurement, time tracking, frequency tracking, noise estimation, or any combination thereof.

10. The method of claim 1 , wherein the pseudo-random sequence and the scrambling sequence are used for both normal cyclic prefix and extended cyclic prefix.

11. A method of generating a reference signal in a wireless communication system, comprising: generating a pseudo-random sequence based on a cell identity (ID) of a cell; generating a scrambling sequence based on the cell ID; generating a reference signal sequence based on the pseudo-random sequence and the scrambling sequence; and generating a reference signal for the cell based on the reference signal sequence; wherein the generating the scrambling sequence includes generating a first sequence having shorter length than the pseudo-random sequence, and repeating the first sequence to obtain the scrambling sequence having same length as the pseudo-random sequence.

12. An apparatus for wireless communication, comprising: at least one processor configured to generate a pseudo-random sequence based on a cell identity (ID) of a cell, to generate a scrambling sequence based on the cell ID, to generate a reference signal sequence based on the pseudo-random sequence and the scrambling sequence, to generate a reference signal for the cell based on the reference signal sequence, to determine a first index and a second index based on the cell ID, wherein the at least one processor is configured to generate the pseudo-random sequence based on the first index, and wherein the at least one processor is configured to generate the scrambling sequence based on the second index.

13. The apparatus of claim 12 , wherein the at least one processor is configured to generate a primary synchronization code (PSC) sequence based on the second index, to generate a secondary synchronization code (SSC) sequence based on the first index, to generate a primary synchronization signal for the cell based on the PSC sequence, and to generate a secondary synchronization signal for the cell based on the SSC sequence.

14. The apparatus of claim 12 , wherein the at least one processor is configured to generate the scrambling sequence based on a maximum length sequence (M-sequence) or Golay complementary sequences.

15. An apparatus for wireless communication, comprising: means for generating a pseudo-random sequence based on a cell identity (ID) of a cell; means for generating a scrambling sequence based on the cell ID; means for generating a reference signal sequence based on the pseudo-random sequence and the scrambling sequence; means for generating a reference signal for the cell based on the reference signal sequence; and means for determining a first index and a second index based on the cell ID, wherein the means for generating the pseudo-random sequence includes means for generating the pseudo-random sequence based on the first index, and wherein the means for generating the scrambling sequence includes means for generating the scrambling sequence based on the second index.

16. The apparatus of claim 15 , further comprising: means for generating a primary synchronization code (PSC) sequence based on the second index; means for generating a secondary synchronization code (SSC) sequence based on the first index; means for generating a primary synchronization signal for the cell based on the PSC sequence; and means for generating a secondary synchronization signal for the cell based on the SSC sequence.

17. The apparatus of claim 15 , wherein the means for generating the scrambling sequence includes means for generating the scrambling sequence based on a maximum length sequence (M-sequence) or Golay complementary sequences.

18. A computer program product, comprising: a non-transitory computer-readable medium having instructions stored thereon, the instructions including: instructions for causing at least one computer to generate a pseudo-random sequence based on a cell identity (ID) of a cell, instructions for causing the at least one computer to generate a scrambling sequence based on the cell ID, instructions for causing the at least one computer to generate a reference signal sequence based on the pseudo-random sequence and the scrambling sequence, instructions for causing the at least one computer to generate a reference signal for the cell based on the reference signal sequence, and instructions for causing the at least one computer to determine a first index and a second index based on the cell ID, wherein the instructions for causing the at least one computer to generate the pseudo-random sequence includes instructions for causing the at least one computer to generate the pseudo-random sequence based on the first index, and wherein the instructions for causing the at least one computer to generate the scrambling sequence includes instructions for causing the at least one computer to generate the scrambling sequence based on the second index.

19. The computer program product of claim 18 , wherein the non-transitory computer-readable medium further includes: instructions for causing the at least one computer to generate a primary synchronization code (PSC) sequence based on the second index; instructions for causing the at least one computer to generate a secondary synchronization code (SSC) sequence based on the first index; instructions for causing the at least one computer to generate a primary synchronization signal for the cell based on the PSC sequence; and instructions for causing the at least one computer to generate a secondary synchronization signal for the cell based on the SSC sequence.

20. The computer program product of claim 18 , wherein the instructions for causing the at least one computer to generate the scrambling sequence includes instructions for causing the at least one computer to generate the scrambling sequence based on a maximum length sequence (M-sequence) or Golay complementary sequences.

21. A method of receiving a reference signal in a wireless communication system, comprising: generating a pseudo-random sequence based on a cell identity (ID) of a cell; generating a scrambling sequence based on the cell ID; generating a reference signal sequence based on the pseudo-random sequence and the scrambling sequence; and processing a reference signal received from the cell based on the reference signal sequence; wherein the generating the pseudo-random sequence includes generating the pseudo-random sequence based on a first index of the cell ID, and wherein the generating the scrambling sequence includes generating the scrambling sequence based on a second index of the cell ID.

22. The method of claim 21 , further comprising: detecting for a primary synchronization code (PSC) sequence from the cell; determining the second index based on the detected PSC sequence; detecting for a secondary synchronization code (SSC) sequence from the cell; and determining the first index based on the detected SSC sequence.

23. The method of claim 21 , wherein the processing the reference signal includes multiplying received symbols comprising the reference signal with symbols of the reference signal sequence to obtain detected symbols.

24. The method of claim 21 , further comprising: deriving a channel estimate for the cell based on the reference signal.

25. The method of claim 21 , further comprising: performing at least one of signal strength measurement, signal quality measurement, time tracking, frequency tracking, or noise estimation based on the reference signal.

26. An apparatus for wireless communication, comprising: at least one processor configured to generate a pseudo-random sequence based on a cell identity (ID) of a cell, to generate a scrambling sequence based on the cell ID, to generate a reference signal sequence based on the pseudo-random sequence and the scrambling sequence, and to process a reference signal received from the cell based on the reference signal sequence; wherein the at least one processor is configured to generate the pseudo-random sequence based on a first index of the cell ID, and to generate the scrambling sequence based on a second index of the cell ID.

27. The apparatus of claim 26 , wherein the at least one processor is configured to detect for a primary synchronization code (PSC) sequence from the cell, to determine the second index based on the detected PSC sequence, to detect for a secondary synchronization code (SSC) sequence from the cell, and to determine the first index based on the detected SSC sequence.

28. The apparatus of claim 26 , wherein the at least one processor is configured to derive a channel estimate for the cell based on the reference signal.

29. The apparatus of claim 26 , wherein the at least one processor is configured to perform at least one of signal strength measurement, signal quality measurement, time tracking, frequency tracking, or noise estimation based on the reference signal.